Programming in C - Fundamental Study of Strings

Programming in C - Fundamental Study of Strings

1. Strings Introduction Reading and displaying strings Passing strings to function String handling functions C. P. Divate

2. Str i ng s a r e ar r a y of cha r ac t e r s i . e. th e y a r e ar r an g ed on e a f t er another in Thus , a cha r ac t er ar r a y i s c al l ed cha r ac t e r s memory. string. E ach c h a r ac t er within the s tri n g i s s t o r ed within one element of the array successively. A s tring i s a l w a y s t ermin a t ed b y a null character (i.e. slash zero \0 ). Introduction

3. Ope r a t i on s per f o rm e d on include: Reading and writing strings Copying one string to another Combining strings together Comparing strings for equality Extracting a portion of a string cha r ac t er s tr i n g s Arrays and Strings…

4. A string variable is declared as an array of characters. Syntax: char string_name[size]; E.g. char name[20]; When the compiler assigns a character string to a character array, it automatically supplies a null character (‘\0’) at the end of the string

5. Strings are initialized in either of the following two forms: char name[4]={‘R’,‘A’,‘M’, ‘\0’}; char name[]={‘R’,‘A’,‘M’, ‘\0’}; char name[4]=“RAM”; char name[]=“RAM”; When we initialize a character array by listing its elements, the null terminator or the size of the array must be provided explicitly. Initializing String Variables R A M \0 name[0] name[1] name[2] name[3]

6. Reading and displaying Strings It can be done manually.

7. Using printf() and scanf()

8. Using gets() and puts()

9. Passing String to function

10. String handling functions Strings need to be manipulated by programmer. It can be done manually but is time consuming.

11. #include <stdio.h> #include <conio.h> void main() { char input_string[50]; int i=0, length=0; clrscr(); printf("\nEnter your text:\t"); gets(input_string); w hil e( in p ut_ s tr i ng [i]! = ' \0') { l e ngt h ++ ; i++; } printf("\nThe length of your text is: %d character(s)", length); getch(); } Counting length of the string

12. #include <stdio.h> #include <conio.h> void main() { char copy[50], paste[50]; int i; clrscr(); printf("\nEnter your name (to copy):\t"); gets(copy); for(i=0;copy[i]!='\0';i++) { paste[i]=copy[i]; } paste[i]='\0'; printf("\nThe name is (pasted as):\t"); puts(paste); getch(); } Copying one string to another

13. There are various string handling functions define in string.h some of them are:

14. void main() { char input_string[50]; int length; clrscr(); printf("\nEnter your text:\t"); gets(input_string); length=strlen(input_string); printf("\nThe length of your text is: %d character(s)", length); getch(); } 14

15. void main() { char copy[50], paste[50]; int i; clrscr(); printf("\nEnter your name (to copy):\t"); gets(copy); strcpy(paste, copy); printf("\nThe name is (pasted as):\t"); puts(paste); getch(); } 15

16. void main() { char first_name[30]=“College " ; char middle_name[]=" of Applied"; char last_name[]=" Business"; clrscr(); s t rca t ( f i rs t _ n am e , m iddle_ n am e ); puts(first_name); strcat(first_name,last_name); puts(first_name); getch(); } 16

17. void main() { char str1[30],str2[40]; int diff; clrscr(); printf("Enter first string:\t"); gets(str1); printf("\nEnter second string:\t"); gets(str2); diff=strcmp(str1, str2); if(diff>0) printf("\n%s is greater than %s by ASCII value difference %d", str1, str2, diff); else if(diff<0) printf("\n%s is smaller than %s by ASCII value difference %d", str1, str2, diff); else printf("\n%s is same as %s", str1, str2); getch(); } 17

18. void main() { char string[25]; clrscr(); printf("\nInput string to be reversed:"); gets(string); strrev(string); printf("\nThe reversed string is: %s", string); getch(); } 18

19. String is array of characters. Thu s a n ar r a y of s tring i s 2 -D ar r a y of characters. E.g. char names[5][10]; Here, names[5][10] means 5 names having 10 characters each. 19 Arrays of Strings

20. Classwork WAP to read name of 5 persons using array of strings and display them WAP to sort name of 5 persons in alphabetical order

21. void main() { char names[5][10]; int i; clrscr(); printf("\nEnter name of 5 persons:"); for(i=0;i<5;i++) scanf("%s", names[i]); printf("\nThe names are:"); for(i=0;i<5;i++) printf("\n%s", names[i]); getch(); } 21

22. void main() { char names[5][10],temp[10]; int i, j; clrscr(); printf("\nEnter name of 5 persons:"); for(i=0;i<5;i++) gets(names[i]); for(i=0;i<5;i++) { for(j=i+1;j<5;j++) { if(strcmp(names[i], names[j])>0) { strcpy(temp, names[i]); strcpy(names[i], names[j]); strcpy(names[j], temp); } } } printf("\nNames in ascending order:\n"); for(i=0;i<5;i++) put s ( na m e s [i ] ); getch(); } 22